Composite fiber materials and, in particular, composite fiber mats are becoming more and more popular as starting materials for support components in motor vehicles. A composite fiber material generally consists of two main components, namely an embedding matrix and reinforcing fibers, wherein the interaction between these two components makes it possible to achieve properties that are superior to those of other composite materials, for example with respect to stability and low weight. The matrix of the composite fiber mat largely determines the appearance of the composite fiber mat and mechanically holds in position the reinforcing fibers, as well as transmits and distributes tensions between the fibers. The matrix may further protect the fibers from external mechanical and chemical influences. The fibers provide the composite fiber mat with the required strength. They absorb mechanical stresses and provide the material with tensile strength, compressive strength and bending strength.
The composite fiber material may be compressed and formed in a pressing tool in a preheated state in order to produce a preform or semifinished product that can be processed into a support plate of a motor vehicle component in further processing steps. These further processing steps may include, for example, laminating a cover layer on the component, forming the component to its final three-dimensional shape and integrally attaching other components.
Preforms of multilayer fiber mats as described, for example, in DE 10 2010 041 179 A1, DE 10 2012 021 738 A1 and EP 2 246 180 A2. The composite fiber mats described in these documents are produced of several layers that are bonded or sewn together.
In motor vehicle components, locally different stresses occur in different regions of the components during their production and use. During the production of the components, the occurring tensile and bending stresses may be higher in certain locally limited regions than in other regions due to the three-dimensional shaping of the support plate. Locally different stresses can also occur during the use of the component. On an interior door panel, for example, the region of the door handle or the region of the map pocket is subjected to higher tensile forces than other regions. On a cargo floor, higher stresses can be expected to occur in the central, well accessible region than on the edges. In case of a collision, the probability of a high compressive point load is also higher in certain regions of the motor vehicle component than in other regions, for example in the region of the dashboard compared to the front passenger seat or certain parts of the car body.
It may therefore be desirable to locally reinforce support components of the motor vehicle without increasing the overall weight of the motor vehicle component or at least without thereby increasing the weight more than necessary.